Abstract # 1732 Exposure to a social stressor results in changes to microbial-produced short chain fatty acids and increased TNF-alpha production by colonic epithelial cells

Abstract

There is increasing evidence that stressor exposure results in significant community-wide changes in the composition of the colonic microbiota. However, whether stressor exposure also changes the metabolic activities of the microbiota is not yet known. Microbes in the colon produce short chain fatty acids (SCFA), primarily butyric, acetic, and propionic acids. These SCFAs have multiple effects on host physiology, and have been proposed to play an important part in the pathogenesis of intestinal diseases. To determine whether stressor exposure would change the levels of microbial-produced SCFAs, mice were exposed to repeated social defeat for 2 h a day on 6 consecutive days. Colonic contents were then removed and levels of butyric, acetic, and propionic acids measured using gas chromatography-mass spectrometry. In addition, SCFA receptor expression was measured and cytokine mRNA was measured in colonic epithelial cells. Exposure to the SDR Stressor resulted in significant reductions in butyric and acetic acid levels in the colon. Interestingly, propionic acid levels were significantly increased in stressor-exposed mice. In addition, exposure to the stressor significantly increased TNF-alpha mRNA in colonic epithelial cells. These data indicate that levels of microbial-produced metabolites are significantly changed in the colon during stressor exposure. Because SCFAs strongly affect cytokine production by colonic epithelial cells, it is possible that stressor-induced changes in SCFAs exacerbate colonic inflammation. Supported by NIH Grant AT006552-01A1.